Individual Data Corruption, Loss, Etc.

[Piotr]

You lost it, not me.

Restore your data from automatic backups in Main Menu -> Settings & Tools -> Tools -> there.

iMtG backups the data automatically before each Database Update and app upgrade.

Beyond that, follow Apple system backup and restore advice.

Beyond that, hire professionals. I'm not gonna help you restore your data, I don't have free time for this. I recommend these people: https://propercode.co.uk